A conventional ultrasonic diagnostic apparatus collects three-dimensional data (volume data) by using a two-dimensional (2D) array probe and a mechanical four-dimensional (4D) probe and displays an ultrasonic image obtained by performing volume rendering on the collected volume data. When the ultrasonic image is displayed, the ultrasonic diagnostic apparatus can display an ultrasonic image obtained by performing volume rendering on voxel data. Note that the voxel data is obtained by converting coordinates of the volume data into those in a three-dimensional Cartesian coordinate system constituted by XYZ coordinates.
A shear warp method has been known as a method of performing volume rendering at a high speed in recent years. The shear warp method is a rendering method using the above-mentioned voxel data. With the shear warp method, pieces of sliced voxel data are rearranged in accordance with change (rotation) in the sight line direction so as to perform the volume rendering at a high speed. With the above-mentioned technique, it is difficult to prevent image quality from being lowered efficiently in some cases.